Most comprehensive write up of JPEG et al. I have ever come across.

I think the MozJPEG compression optimisations deserves a mention, as does where we started, with RLE encoding for printer things.

Also important for my personal understanding of JPEG is the context: slow CPUs and analogue screens. OG JPEG was optimised for this, MozJPEG changed the look up tables and the ubiquitous 'turbo' JPEG library to use a few more CPU cycles and save a few more bytes, whilst fixing the banding that was actually okay in the analogue days of old CRT monitors.

Bookmarked the article for re-reading.